How to select the sewage flow meter?

This article mainly details the selection of sewage flow meter. If you feel that the answer is helpful to you, please raise your hand to the U.S. Weidun VTON flowmeter point a praise!

Because sewage has a large change in flow, containing impurities, conductivity and corrosive characteristics, so sewage flowmeter, paint imported sewage flowmeter selection is more complex. Can be used for sewage flowmeter is mainly imported electromagnetic flowmeter, imported ultrasonic flowmeter, imported V cone flowmeter; this paper is mainly from the measured medium object, flowmeter performance, installation conditions, use of the environment, economic costs and other five aspects, with reference to the VTON selection program, the selection of imported sewage flowmeter for comparative analysis of the flowmeter for the sewage flow monitoring process flowmeter to provide a reference for the reasonable selection.

Sewage, especially untreated sewage, not only has a strong corrosive, but also contains a large number of impurities, with a certain degree of conductivity, and at the same time the selection involves a number of technical issues and economic factors. Therefore, to be technically feasible, economically rational, must have an understanding of the performance characteristics of the flow meter and the principle of operation, in order to ensure that the flow meter selection more reasonable. In this paper, through the introduction of several commonly used flowmeters, according to the actual application, explaining how to rationally select different flowmeters in the process of sewage flow monitoring.

Selection of sewage flowmeter

(a), a clear object to be measured

The object to be measured is industrial wastewater, industrial wastewater contains a large number of impurities, there is a certain degree of conductivity and corrosiveness, imports of electromagnetic flowmeter is the most appropriate; electromagnetic flowmeter is suitable for measuring the conductive liquid (conductivity ≥ 5 μS/cm) of the flow rate should be measured according to the measured media physical properties, pipeline materials. According to the nature of the measured medium, pipe material, reasonable choice of electrode form, electrode material, lining material, grounding, protection level.

Ultrasonic flowmeter on the measured medium requirements are very harsh, like the Doppler method of ultrasonic flowmeter can only be normal measurement of impurity content is relatively stable fluid, and time difference method flowmeter is mainly used to measure the clean fluid.

2, imported V cone flow meter for dirty fluid measurement, but the prerequisite is the Reynolds number should meet the requirements. When the Reynolds number of unlimited decline, V cone flowmeter outflow coefficient as the Reynolds number decreases, its uncertainty will increase. In high-pressure occasions, V cone flowmeter use has limitations, because the structure of the cone negative pressure tube in the case of high pressure to withstand will fall off, resulting in accidents, selection should be noted.

(B) flowmeter performance

1, in the selection of a certain flowmeter, should first be considered in a comprehensive manner the accuracy of the flowmeter, repeatability, linearity, range ratio, pressure loss, the output signal characteristics, response time, non-detectability and other factors. Electromagnetic flowmeter sensor structure is simple, the measurement tube does not have any obstacle to the flow of the medium throttle parts, so it will not cause any additional pressure loss, is one of the lowest energy-consuming flow meter flow meter. Electromagnetic flowmeter range is very wide, and in the measurement process is not subject to the measured medium temperature, viscosity, a certain range of conductivity, responsive, can provide a wide range of choice of caliber, from a few millimeters to 3m can be satisfied, the choice of electromagnetic caliber should be guaranteed to ensure that the minimum flow conditions measured medium flow rate of not less than 0.5m/s.

Ultrasonic flowmeter is a non-contact measurement instrument, no mechanical transmission. Measuring instrument, no mechanical transmission parts, no obstruction in the channel, no pressure loss, energy loss, measurement accuracy is not high.

Imported V cone flowmeter is a new type of flowmeter with unique performance, high precision, high stability, wider range, and good repeatability (≤ 0.1%), high accuracy (≤ 0.5%). Because it relies on the throttling effect to measure the pressure difference, so there is a certain pressure loss.

Many flow meters in the operation of the process of problems, mostly due to installation problems. Electromagnetic flowmeter horizontal, vertical (bottom into the top), inclined (bottom into the top) installation can be, but the requirements of the front, after the need to have a straight section, the general requirements are the front straight section is greater than or equal to 5D, after the straight section is greater than or equal to 3 D. Electromagnetic flowmeter should be installed to ensure that the full flow of the pipe, can not be installed at the highest point of the pipe. Instrumentation wells installed in the electromagnetic flowmeter sensor protection level should be IP68.

Ultrasonic flowmeter installation of the front and rear straight section of the higher requirements, the installation position should be at least 15D straight section length, can not be affected by the vibration, otherwise the measurement is not accurate.

Imported V cone flowmeter installation is very easy to use, flexible installation, optional pipe flange, direct welding, square pipe type, the required straight pipe section is very short, the front straight pipe section is less than or equal to 3D, after the straight pipe section is less than or equal to 1D can meet the requirements. When the measurement of dirty media, should be a reasonable choice of V cone flowmeter to take the pressure, to avoid clogging of the measurement pipeline.

(D) environmental

1, the environment is mainly to consider the surrounding temperature, humidity, security factors, signal conditioning and transmission, pressure, atmospheric and electronic interference, etc. on the stability of the performance of the flowmeter aspects of the impact. Installation should try to avoid large motors, large transformers, etc., in order to prevent the introduction of electromagnetic interference.

Electromagnetic flowmeter ambient temperature is generally -30 ~ 80 ℃, the requirements of relative humidity between 5% ~ 95%, the atmospheric pressure of 86 ~ 106kPa;

Imported ultrasonic flowmeter on the ambient temperature requirements for: the converter is -10 ~ 45 ℃, sensors are -30 ~ 60 ℃ (room temperature type) and -30 ~ 160 ℃ (high temperature type);

And V cone flowmeter ambient temperature in the range of -25 ~ 60 ℃, the temperature of the one-piece structure is also subject to electronic components, the range to be a little narrower, the ambient relative humidity in the range of 10% ~ 90%. The ambient relative humidity is in the range of 10% to 90%.

(E) economic cost

The choice of flowmeter to be in the initial investment and long-term reliable operation between the comprehensive consideration, such as the purchase cost, installation costs, operating costs, maintenance costs, calibration costs, flowmeter life, spare parts and consumer goods, reliability and other factors should be effectively meet the premise of reliable operation of industrial production, the optimal economic Selection;